Telecom Wavelength Light At Room Temperature

Scientists have developed the first room-temperature, electrically driven, topological laser, which could be useful in telecom wavelength applications. The novel device comprises a 10 by 10 grid of 30-micron-wide rings. Small oblong rings around 5 microns wide connect these rings. All these rings consist of a sandwich of layers of semiconductors, such as indium gallium arsenide, indium phosphide, and indium gallium arsenide phosphide.

The novel topological laser’s 10 by 10 grid of rings served as multiple coupled resonators. The rings generate laser light at a wavelength of 1.5 microns, the most common wavelength (telecom wavelength) utilized in fiber optic communications when electrodes at the array’s edge electronically pump this grid.

The size and shape of the rings, their position to one another, and the thicknesses and composition of the semiconductor layers all contribute to the topological protection of the laser’s light. Topological photonics has enabled interconnection between multiple resonators, allowing for new and improved functionality.

Even though some of the rings were missing, topological protection allowed the laser to function. The topology of the device also contributed to ensuring that the light emitted was almost entirely of the desired wavelength—a similar array with rings in slightly different positions, and thus a different topology, emitted a less pure spectrum of light made up of several different wavelengths.

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